What is plastic extrusion? In a basic technical definition, it is the transformation of solid plastic mass converted into a shape. That can be used as produced or converted into usable products. Plastic extrusion is a mass manufacturing process.The raw plastic is about to melt and form a continuous outline.
This process starts by feeding plastic material (pellets, granules or flakes ) from a hopper into the barrel of the extruder. The material is melted by the mechanical energy generated by turning screws and by heaters arranged along the barrel. The molten polymer is then forced into a die. Which shapes the polymer into a shape that hardens during cooling.
plastic films and sheeting
and wire insulation.
Plastic extrusion is used in three main processes to produce plastic parts. That includes extrusion, injection molding and blow molding. There is a uniqueness to each primary process. Extrusion molding is continuous. Injection molding is discontinuous. And blow molding is also considered continuous.
Extrusion is a continuous process of converting a solid plastic mass, pellet or powder into a melted form where it is pushed through a die into a shape. This shape is then moved through various secondary operations. Where it is cooled then cut, coiled or experiences a variety of other possible operations.
Each sub-process is unique requiring different dies, post extrusion or downstream equipment to produce the desired product. Regardless of the process, each sub process has a single component in common, an extruder.
Plastic extrusion is a high-volume manufacturing process. The raw plastic will melt and form a continuous contour. Products produced by extrusion include pipes / tubes, weather strips, fences, deck railings, window frames, plastic films and sheets, thermoplastic coatings and wire insulation materials.
The extruder's job is to transform the solid plastic mass or feed stock into a melted form. To do this are two core extruder technologies, single and twin screw. The single screw extruder is the most widely used technology for extrusion. It has the versatility to process a wide variety of polymer types and can be applied to all common extrusion processes.
The extruder is often called the heart of the extrusion process. Taking this a step further, the extruder screw is frequently called the heart of the extruder. Why is the extruder screw the heart of the extruder or the extrusion process itself? Because if the extruder screw does not perform at an optimum level the rest of extrusion process will suffer. This is why the screw has been the most studied component of the extrusion process outside of polymer chemistry.
Q: How do you improve extrusion process?
A: Adjust feed throat temperature.
Maintain a consistent regrind form.
Cool screws when processing polymers to minimize degradation.
Use only treated water in your closed-loop, water-cooled barrel system.
Align extruder barrels as part of the maintenance procedure.
Q: What does an extruder do?
A: An extruder is simply the machine used to complete the extrusion process. Using a system of barrel and screw, the machine heats up the product and propels it through the die to create the desired shape.
Q: How many types of extruder are there?
A: classify by the number of extruder screw there are two types: single screw extruder & twin screw extruder. Classify by the extruder structures there are two types: vertical extruder & horizontal extruder. Classify by the plastic materials of extruder there are more than 20 types such as PVC extruder,rubber extruder,silicone extruder,fluoroplastics extruder etc.
Q: How do you compress plastic?
A: As the raw material reaches the barrel, a long shearing screw, which rotates at certain RPM, pushes the plastic granules forward in to the heated chamber and be compressed.
There are two ways the plastic is melted:
a. by passing the raw material through the heating zones
b. by the friction and pressure that the raw material encounters
With the combination of the two heating actions, the material steadily reaches the melting point. For some applications, there is no need for heating zones when heat produced by friction is enough to melt the plastic.